hot water at pressure 125 - what does this say about 13yr hot water heater

Hi all,

I have a tanked hot water heater, 13 years old, that I am thinking is reaching the end of it's useful life, but wanted to get some expert opinion before replacing.

Current problem we are seeing
Hot water is venting via a wilkins 1500 valve (graduated screw in type) from the hot water side of the tank, to a pvc pipe and then to outside. It's been doing this for a number of weeks. Currently the wilkins valve is set to 125.

Note that this wilkins is inline with the hot water pipe exiting the tank and is separate from the TPR valve on the side of the tank. I don't know why I have this extra valve. I operated the TPR valve and it is working; vents when I pull it and stops when I release it.

Anyways, since the wilkins is set to 125, is that a high or low pressure for hot water or do I have room to play to alter it to stop this venting? (perhaps dangerous given it's a safety valve).

And what does this venting and the 125 value say about the health of the hot water heater?

Note that we don't have any complaints about the temperature or pressure of hot water into the house.

put an actual pressure gauge on the system and see what the actual pressure is. Maybe the valve is failing.

Do you mean measure the hot water pressure. How would I that since I am only familiar with the pressure gauges that fit on an outside faucet for the cold water. I guess I could cut in and add a suitable connector to one of the hot water pipes and measure from that.

I got a basic water pressure test gauge from Lowes (orbit model #91130) and tested both the hot and cold lines for pressure.

With no faucets on or any other items drawing water, cold is at 98psi and hot (or not so hot since its not really running at the time of test), at little over 100psi. So not good.

Could it be my Pressure Regulator Valve is faulty and not stepping down the pressure from the street? I should also have mentioned that when we have two faucets on at the same time and we get a wining sound from the plumbing. It doesn't bang, just a whine, medium pitch.

I plan to get a second, better test gauge later this week since I don't think I should rely on one test and one gauge. Will get something more robust from a professional plumbers supply place - just can't get there today with work etc.

As for my location, and I only mention this because the Lowes guy asked, am located in Cobb County, suburb of Atlanta and Lowes guy said my pressure should be around 45-50 something.

With the test gauge attached to the cold line it reads 98psi with no faucets or water being drawn. If I turn on a faucet on the same floor as the gauge, the pressure drops to 40psi. Then turn off the faucet and the pressure climbs back to 98psi and takes about 30-60 seconds.